Bulk processing of food products is required in industry and many foods are stored at lower temperatures for sanitary purposes to prevent rapid growth of bacteria and spoilage. The very process of cooling lowers the dew point and thus tends to dehydrate food. When large quantities of food products need be processed quickly as when conveyed through a food chiller on a moving belt, it has been difficult to chill them without spending considerable energy and without dehydration, which damages both appearance and flavor. Thus, use of cold air or freezing gases such as CO.sub.2 has been done in a very low humidity atmosphere. Also the amount of energy required for freezing food is disproportionately large as compared to the energy required to bring the food temperature to the vicinity of 0.degree. C.
Examples of prior art of this nature are as follows:
Certified Manufacturing, Inc. of Lynwood, Calif. 90262, has marketed a conveyor belt type food processor freezing the food in the presence of CO.sub.2 gas.
U.S. Pat. No. 2,846,318--E. J. Kelley et al.--Aug. 5, 1958 uses low pressure water vapor with droplets which are evaporated from the surface of the product. This could not be done, for example, with some food products such as breaded fish, meat or chicken parts since the surface appearance and texture would be altered.
U.S. Pat. No. 3,412,476--S. Astrom--Nov. 26, 1968 passes conveyor belts through a spiral path in a chiller compartment with cold air as a refrigerant.
In addition to the energy inefficiency and the dehydration tendencies of large capacity, rapid food chillers of the prior art, there are many problems relating to sanitation. When conveyors carry food products through a chiller unit there are impurities and contamination that can accumulate along the conveyor tracks and in the chilling system, thus requiring frequent sanitation.
Most prior art systems are ill constructed to permit the critical access, cleaning and sanitation features required by licensing authorities in food processing plants.
Accordingly, it is an objective of this invention to improve the foregoing defects of the prior art by supplying efficient rapid chilling apparatus and methods for processing large quantities of food such as are handled on a continuously running conveyor.
Other objects, features and advantages of the invention will be found set forth hereinafter.